MB-11053: Don't create a new failover entry for upr set vb state

We were incorrectly creating a new failover entry when there was
a clean handoff through an upr takeover stream. Whenever there is
a clean handoff we should not generate a new failover entry.

Change-Id: If36055274e867032cc752407eff8aee39bff32ba
Reviewed-on: http://review.couchbase.org/37643
Reviewed-by: Chiyoung Seo <chiyoung@couchbase.com>
Tested-by: Michael Wiederhold <mike@couchbase.com>